SN 2018zd

Information about outbursts of eruptive stars, Be activity, ...

Re: SN 2018zd

Postby Peter Somogyi » Wed Mar 14, 2018 1:55 pm

Wow Robin, that SN 2003hy in your adsabs link transformed to a so different shape within 1 month! (but nothing in between)
Also surprising how different days are estimated (-15, -100: ?).
I'm trying to google for an example spectrum serie of type IIn, but can't find any yet.

- Peter
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Re: SN 2018zd

Postby Peter Somogyi » Thu Mar 15, 2018 1:07 pm

Hi Robin,

After some surfing and browsing, I've found a good web page to compare our spectrum serie - with this nice interactive serie browser (you can magnify into the serie, shown stacked, a tooltip shows day to max etc..):

"The Open Supernova Catalog"
http://sne.space
<type in search box "IIn", then order column by - number of - 'Spec.'>

My findings, browsing the most observed ones:
SN2009ip got at first (260 spectra), however magnifying into it tells our serie is very much different.
The 2nd, SN1998S (78 spec.) show a very good serie-wise match via human look so far having P-Cyg (I may browse it further with time), but like I wrote, its velocities are much narrower. (Also missing observation between days 15-55 although the change is big.)
Further SNs either not resembling or have poor coverage or SNR (also see Mmax, till 15mag only a few non-matching are there).
For "SN2003hy" (Mmax=16), this page tells "Type II", and does have a good coverage after 0-day (before is missing), but rather noisy (I guess your graph or SNID may be smoothing it). The velocities and continuum really match on your graph at least.

I recommend this tool to everyone (besides Gelato, SNID), giving a more global picture speculate how the serie and magnitude is expected to evolve, and how much a similar SN (further than type categorization) is explored.

Cheers,
Peter
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Re: SN 2018zd

Postby Robin Leadbeater » Thu Mar 15, 2018 11:50 pm

Hi Peter,

Yes and because OSC scrapes data from TNS it even includes some of my spectra and you can also add spectra to it directly (I was invited after my spectra appeared on TNS) Take care though. The spectra used by SNID (and GELATO) were chosen because they have a reliable known classification and are representative of the type.

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: SN 2018zd

Postby Robin Leadbeater » Fri Mar 16, 2018 12:01 am

Filippenko's paper "optical spectra of supernovae" gives a good overview of supernovae spectra and how they evolve
https://www.annualreviews.org/doi/abs/1 ... o.35.1.309

EDIT: Oops! the published version is behind a paywall but you can find it here as part of his course material at caltech
http://ned.ipac.caltech.edu/level5/Marc ... tents.html

Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: SN 2018zd

Postby etienne bertrand » Wed Mar 21, 2018 12:12 pm

Un spectre prit cette nuit. Très peu de raies.... Gelato l'indique comme IIn
Image
Image
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Re: SN 2018zd

Postby Peter Somogyi » Sun Mar 25, 2018 2:21 pm

Hi Robin,
Thanks for the useful links, I've read them by now. It is telling type IIn can be more versatile.

Hello Etienne,
It looks also on your spectrum the Balmer increased earlier than seen for other IIn types. It has motivated me to revisit this object.
Here is mine from 2018-03-24, as the last in my evolution serie:
sn2018zd_serie.gif
2018-03-22: 15 x 1200s, ATIK 414 EXm, Alpy 600, 18u slit, 300/1200 Newton, eq6
sn2018zd_serie.gif (83.89 KiB) Viewed 485 times

Gelato yet reporting unknown type bringing 2009bw IIP on front, but many of type IIn with 1998S as the next - however, Balmer increase looks happening earlier than in case of 1998S:
sn2018zd_gelato_1998S_IIn.gif
sn2018zd_gelato_1998S_IIn.gif (28.4 KiB) Viewed 485 times

Cheers,
Peter
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Re: SN 2018zd

Postby Forrest Sims » Sun Mar 25, 2018 6:23 pm

Hi Peter and Robin,

I made a last attempt to see if I could capture data on SD 2018-zd last night. It is very faint and I had to use 6 second exposures with a LodestarX2 to guide on it.

The data is also very noisy with only 8 300sec exposures. (I should have taken 600sec exposures as you did but I was worried about loosing the target between the time it got dark and the target set too low.) But if I play with the Gaussian filter in ISIS, I can clearly see emission lines similar to Peter’s 2018-03-22 data for Hepsilon, Hbeta and Halpha. The continuum continues to flatten in the visible wavelength band. Here is the filtered profile with a Gaussian filter value 6 followed by the unfiltered data.

Do you think I am interpreting data this correctly?

Cheers!
Woody
Attachments
sn2018zd_20180325_144_Forrest Sims Gaussian filter6.png
Smoothed with Gaussian filter 6
sn2018zd_20180325_144_Forrest Sims Gaussian filter6.png (35.41 KiB) Viewed 483 times
sn2018zd_20180325_144_Forrest Sims.png
sn2018zd_20180325_144_Forrest Sims.png (67.34 KiB) Viewed 483 times
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Re: SN 2018zd

Postby etienne bertrand » Sun Mar 25, 2018 8:39 pm

Good works Peter and Forrest,
300s is a little too short (binning ?), but there is visible emission (Ha and Hb), with 600s or 900s ths SNR will be good.
This SN is very difficult !
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Re: SN 2018zd

Postby Peter Somogyi » Sat Apr 14, 2018 7:47 pm

Hello,

I wanted to have a serie finisher for SN2018zd, last night got the chance:
sn2018zd_20180413_gelato.png
tons of exposure (13 x 20 minute), suitable for the 14.1 Vmag
sn2018zd_20180413_gelato.png (116.24 KiB) Viewed 327 times

It's being stuck at 14.1 mag for a long time.
Gelato suggests "91% type II", with all the mostly offered IIn samples (most of them 1998S) having somewhere different absorptions.
Finally, good to see that it's not a simple repeat of an already categorized type.

- Peter
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Re: SN 2018zd

Postby Forrest Sims » Wed Apr 18, 2018 9:01 pm

Hi Peter, Etienne and Robin,

I had to try Peter’s challenge and get one more dataset on this target. I used HD072660 as the Reference star. I took 8 600sec images of the target. I had to use a nearby star with 5 sec exposures for guiding as I could not guide on the bits of target starlight on the top and bottom of the slit. I could not find the source of the false emission lines at about 5784Å and about 6306Å. I added some additional pixels that looked suspect to the cosme file and tried with and without he Cosmic Ray filter. But after hours of examine the data, I still do not see the cause. This plot is without using the Cosmic Ray filter since it appears to fix some problems but creates other huge spikes at other wavelengths.

Cheers!
Woody
Attachments
sn2018zd_20180418_146_forrest Sims.png
sn2018zd_20180418_146_forrest Sims.png (65.33 KiB) Viewed 277 times
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